Tree canopy study tracked 1,031 older Australians
Older Australians living in areas with more tree canopy had fewer depressive symptoms over time in a study of 1,031 people aged 70 to 90.
UNSW Sydney’s Centre for Healthy Brain Ageing, or CHeBA, ran the research with Australian Catholic University. The team followed participants from CHeBA’s Sydney Memory and Ageing Study for up to 12 years.
Researchers examined neighbourhood features near each home, including tree canopy, parkland, access to oceans, rivers and lakes, access to amenities and air pollution.
According to the study in the Journal of Affective Disorders, the strongest and most consistent result linked greater long-term exposure to tree canopy with lower levels of depression.
Lead author UNSW Scientia Associate Professor Simone Reppermund said, “Trees provide far more than shade and visual appeal.”
Reppermund said neighbourhoods with more tree cover may help older people spend time outdoors, stay physically active and connect with their communities. She linked those habits to better mental health in later life.
Journal of Affective Disorders study
The team also tested parkland, blue space, access to services and long-term exposure to lower air pollution. Those measures did not show the same consistent link with depressive symptoms after the researchers accounted for other environmental factors.
Depression affects almost one in five adults over 60 worldwide. The condition is linked to poorer physical health, cognitive decline, reduced independence and lower quality of life.
Co-author Professor Ester Cerin, a behavioural scientist at ACU’s Mary MacKillop Institute for Health Research, said the findings support neighbourhood design that helps healthy ageing.
Cerin said increasing tree canopy may help create communities that support physical activity, social interaction and mental wellbeing across the lifespan. She also said no single environmental feature can prevent depression on its own.
Researchers then tested whether changes in neighbourhood environments over time shaped mental health. At first, some results looked surprising because increases in tree canopy and reductions in nitrogen dioxide, or NO₂, appeared to align with higher depressive symptoms.
However, further analysis pointed to relocation as the main reason for that pattern. Many participants who moved did so because of declining health or because they entered residential aged care, where greener surroundings are often more common.
As a result, the researchers concluded those later findings reflected life circumstances rather than harm from trees or cleaner air. The long-term pattern still favoured greater tree canopy.
The study highlights a possible role for urban planning in healthy ageing. In this analysis, tree cover stood out more clearly than parkland, water access, amenities or air pollution measures.
